Lucy loved the land, new research suggests. A study in this week’s edition of the journal Science puts forth a foot bone from the early hominid Australopithecus afarensis (Lucy’s kind) as evidence that this species was built for walking—meaning human ancestors could have been striding around on ground level for most of their lives by 3.2 million years ago.
Scientists already knew that A. afarensis could walk on two feet but were unsure whether the creatures climbed and grasped tree branches as well, much like their own ancestor species and modern nonhuman apes. The fourth metatarsal … shows that A. afarensis moved around more like modern humans. “Now that we know Lucy and her relatives had arches in their feet, this affects much of what we know about them, from where they lived to what they ate and how they avoided predators,” said Carol Ward. [The Guardian]
The bone in question comes from Ethiopia, home to many significant hominid finds. And though it is just a small sample, that arched shape in the foot bone suggests Australopithecus had rigid feet, and may not have been much better at climbing trees than you or I.
Arches were an important part of our evolution into humans, because they make climbing trees much harder. The arches on the inside of the foot, nearer to the big toe, serve as a shock absorber when we plant our feet back on the ground. All other living primates have feet made for grasping and bending to hang onto tree branches and their young, more like our hands than our feet. [LiveScience]
Babies: As we reported yesterday, they just keep getting bigger. And while they haven’t always been trending towards obese, human babies have always been larger, relative to their mothers, than the infants of most other species. This make birth difficult and could have even changed the social structure of early hominids, steering human evolution.
Human babies are about 6.1 percent of their mother’s weight at birth, while chimp babies are about 3.3 percent. A new paper published in the Proceedings of the National Academy of Sciences takes a look at our extinct relatives to determine when this shift occurred, and suggests that it could even have encouraged our ancestors to come down from the trees and to form more complex social arrangements.
As anthropologist Jeremy DeSilva of Boston Univeristy pointed out in his new paper, “carrying a relatively large infant both pre- and postnatally has important ramifications for birthing strategies, social systems, energetics, and locomotion.” [Scientific American]
Back in August, a study in Nature attempted to push back the date of human ancestors’ first known tool use by 800,000 years—from 2.6 million years ago to 3.4 million years ago. The evidence was a set of scratches on animal bones, which—according to the scientists behind the study—show evidence that the hominid species Australopithecus afarensis used cutting tools.
Not so fast, some anthropologists say. At the time of the Nature paper, researchers including the scientists behind the 2.6-million-year-old find said the newly found markings could have been caused by other means, including trampling by other animals. Now, in a study (in press) for today’s edition of the Proceedings of the National Academy of Sciences, a team of anthropologists makes a full case that the 3.4-million-year-old scratches are not evidence of tool use.
They argue that similar cuts can be produced when bones are gnawed by animals, trampled into rough ground, or even eroded by plants and fungi. Their conclusion: the marks on the Dikika bones were probably created by trampling and their age is uncertain. To them, the best evidence for butchery by human ancestors comes from stone tools recovered in Gona, Ethiopia, which are just 2.6 million years old.
Check out the rest of this post at Not Exactly Rocket Science.
Not Exactly Rocket Science: Human ancestors carved meat with stone tools almost a million years earlier than expected
80beats: Lucy’s Species May Have Used Stone Tools 3.4 Million Years Ago
DISCOVER: How Loyal Was Lucy?
No offense, Lucy, but at three feet, six inches you were kind of short. Your diminutive, 3.2 million-year-old bones made it difficult to tell whether your species could even walk like us. Fortunately, researchers in Ethiopia have uncovered an older, bigger relative. As described in Proceedings of the National Academy of Sciences, some researchers believe that these new bones show that members of Lucy’s species, Australopithecus afarensis, could walk like modern humans.
The paper’s authors call him Kadanuumuu (kah-dah-nuu-muu)–”big man” in the Afar language. Big Man still isn’t really that big by today’s standard: His 3.6 million-year-old bones show that he stood at around five feet.
The fossilized remains don’t include a head, but Big Man has many of the same bones as Lucy, and also others previously missing: a shoulder blade and a rib cage bits. Lead researcher Yohannes Haile-Selassie argues that Big Man’s skeleton upends previous beliefs about Lucy’s love of tree climbing and more primitive walk.
“This individual was fully bipedal and had the ability to walk almost like modern humans,” said Haile-Selassie. “As a result of this discovery, we can now confidently say that ‘Lucy’ and her relatives were almost as proficient walking on two legs as we are, and that the elongation of our legs came earlier in our evolution that previously thought.” [Cleveland Museum of Natural History]
The ancestors to modern humans really hit their stride 1.5 million years ago. Fossilized footprints found in Kenya were made by hominids that share a common foot anatomy and walking stride with modern humans, researchers say.
Scientists are almost certain that the 1.5-million-year-old prints belong to Homo erectus and that the individuals had heels, insteps and toes almost identical to those in humans, and they walked with a long stride similar to human locomotion…. The prints helped explain fossil and archaeological evidence that erectus had adapted the ability for long-distance walking and running [The New York Times]. There is evidence of a heavy landing on the heel with weight transferred along the outer edge of the foot, progressing to the ball of the foot and lifting off with the toes [BBC].